Department of Epidemiology and Biostatistics, School of Public Health, Capital Medical University.
Center for Clinical Epidemiology and Evidence-based Medicine, Beijing Children's Hospital, Capital Medical University, National Center for Children Health, Beijing, China.
J Hypertens. 2019 Jan;37(1):99-108. doi: 10.1097/HJH.0000000000001879.
Aimed to evaluate the validity of five published equations that estimate 24-h urinary sodium excretion (24-h USE) by timed spot urine specimens.
All of the spot urines within 24 h were collected from 99 healthy volunteers aged 21-57 years. The spot urinary sodium and 24-h USE were measured. The 24-h USE was estimated by INTERSALT equation and Tanaka equation with casual spot urine and four timed spot urines (i.e. overnight, second morning, post meridiem, and evening urine), by Kawasaki equation and SunSMU equation with second morning urine, and by SunPM equation with post meridiem urine, respectively. At last, the agreement between measured and estimated 24-h USE was evaluated.
The average of the measured 24-h USE was 4558.25 ± 1908.75 mg/day. The proportion of participants with more than ±40% of relative difference between measured 24-h USE and estimated 24-h USE by five equations varied from 21.18 to 42.35%. The absolute differences of 24-h USE among approximately half of the participants were more than ±1170.00 mg/day estimated by Kawasaki equation, INTERSALT equation, and SunPM equation, respectively. In addition, misclassification rates of individual salt intake for five equations were more than 60%. It was found that overestimation occurred at low levels of sodium excretion whereas underestimation occurred at high levels of sodium excretion except Kawasaki equation. The 24-h USE estimated using Tanaka equation with four timed spot urine specimens varied substantially, although Tanaka equation with casual spot urine specimen provided the highest correlation coefficient and the least mean difference.
There is still no evidence to support that 24-h USE could be estimated accurately using the current equations, especially for the equations developed by casual spot urine specimens.
评估五种已发表的通过 24 小时时间点尿液样本估算 24 小时尿钠排泄量（24-h USE）的方程的有效性。
收集 99 名年龄在 21-57 岁的健康志愿者 24 小时内的所有时间点尿液。测量尿液钠和 24-h USE。使用 INTERSALT 方程和 Tanaka 方程，通过随机时间点尿液和四个时间点尿液（即夜间、第二次晨尿、下午尿和晚间尿），使用 Kawasaki 方程和 SunSMU 方程通过第二次晨尿，以及使用 SunPM 方程通过下午尿分别估算 24-h USE。最后，评估测量和估计的 24-h USE 之间的一致性。
测量的 24-h USE 的平均值为 4558.25±1908.75mg/天。五种方程中，测量的 24-h USE 和估计的 24-h USE 之间的相对差异超过±40%的参与者比例在 21.18%至 42.35%之间。约一半参与者的 24-h USE 绝对值差异大于 Kawasaki 方程、INTERSALT 方程和 SunPM 方程分别估计的±1170.00mg/天。此外，五种方程的个体盐摄入量的错误分类率都超过了 60%。结果发现，除了 Kawasaki 方程外，在低钠排泄水平时存在高估，而在高钠排泄水平时存在低估。使用四个时间点尿液样本的 Tanaka 方程估算的 24-h USE 差异很大，尽管使用随机时间点尿液样本的 Tanaka 方程提供了最高的相关系数和最小的平均差异。
目前尚无证据支持可以使用当前方程准确估算 24-h USE，特别是对于由随机时间点尿液样本开发的方程。
